The present invention relates to an optical deflection apparatus by which a rotational polygon mirror is rotated, and the light beam scanning is conducted, and to a production method of the optical deflection apparatus and an adhering method which is appropriately used for the production method.
Conventionally, in an electro-photographic system image forming apparatus such as a laser beam printer or a digital copier, an optical deflection apparatus which conducts light beam scanning for writing an image on a photoreceptor drum is used. In such the optical deflection apparatus, an optical deflection apparatus in which a polygon mirror in which a magnet is fixed, is rotatably provided through a bearing, and a coil is provided on the substrate in opposite to the magnet, is widely known (for example, refer to Japanese Tokkaihei No. 8-121471).
However, when the magnet is fixed on a polygon rotor unit by an adhesive agent, there is a problem in which the strain is generated in each part when the temperature variation is generated, and the flatness of the mirror is lacked. Further, a change is generated in the strain by this temperature variation, and the variation is also caused in the balance of the polygon mirror, and when the change of the balance becomes large, the vibration is increased, and as the result, there is a possibility of the deterioration of the image quality of the image forming apparatus or a noise problem. Further, when the temperature variation is generated, there is a problem that the strength of the joint portion by the adhesive agent is easily decreased. Further, as the adhesive agent, when anaerobic adhesive agent is used together with the hardening accelerator including amine organic compound, according to circumstances, there is a problem that a joint portion by the adhesive agent is easily peeled off, and the joint strength is decreased.
In view of the foregoing problems, the object of the present invention is to provide an optical deflection apparatus which can improve the mirror flatness and the balance characteristics of the polygon mirror even when temperature variation is caused.
Further, the object of the present invention is to provide the optical deflection apparatus, and its production method and the adhering method thereof, in which, even when the temperature variation is caused, the joint strength of the joint portion in which each part of the optical deflection apparatus is jointed by the adhesive agent, can be prevented from being decreased, and disadvantages in which the joint portion by the adhesive agent is easily peeled off, are prevented, and the decrease of the joint strength can be prevented.
In order to attain the above objects, the present inventors diligently investigate and find the following: when the temperature variation is caused in the optical deflection apparatus, a strain is generated due to the differential thermal expansion of each part, and the flatness of the mirror, the balance and joint strength are badly affected, and therefore, when each part is adhered by the adhesive agent, by using the adhesive agent whose Young""s modulus after hardening is not more than 100 N/mm2, the strain of each portion due to the temperature variation can be effectively absorbed, and further, the difference of the thermal expansion coefficients between the adhesive agent and each part is considered, and the following is found: when the temperature is specifically risen, it is effective that the gap of each member is filled up by the expansion of the adhesive agent, thereby, the present invention is attained.
Further, in the case where the acrylic anaerobic adhesive agent is used together with the hardening accelerator as the adhesive agent, it is found that: when the ultraviolet ray is irradiated onto the coating surface of the hardening accelerator, corresponding to the accumulated irradiation quantity, the deterioration of the component of the hardening accelerator occurs, and the adhesive agent is not hardened, and due to this, the joint portion by the adhesive agent easily peels off, and from the result, the present invention is attained.
That is, the optical deflection apparatus is characterized in that: it comprises a base member, a coil fixed to the base member, and a rotor unit which rotates to the base member, and the rotor unit has: a rotating body having the polygon mirror; a bearing portion provided on the rotating body; and a magnet fixed on the rotating body in opposite to the coil, wherein the magnet and the rotating body are jointed together by the adhesive agent whose Young""s modulus after hardening is not more than 100 N/mm2.
According to this optical deflection apparatus, because the adhesive agent whose Young""s modulus after hardening is not more than 100 N/mm2, is used, the joint portion of the magnet with the rotating body has the flexibility and is easily deformed, therefore, even when the temperature variation occurs, the strain due to the differential thermal expansion between the magnet and the rotating body having the polygon mirror can be absorbed by the deformation of the adhesive agent. Accordingly, the flatness of the mirror of the polygon mirror can be improved, and further, the change of the balance characteristic is small. Further, the strength of the joint portion by the adhesive agent can be prevented from being decreased due to the temperature variation.
Another optical deflection apparatus of the present invention is characterized in that: it comprises a base member, a coil fixed to the base member, and a rotor unit which rotates to the base member, and the rotor unit has: a rotating body having the polygon mirror; a bearing portion provided on the rotating body; and a magnet fixed on the rotating body in opposite to the coil, wherein the thermal expansion coefficient of the rotating body is not smaller than the thermal expansion coefficient of the magnet, and the magnet and the rotating body are jointed by the adhesive agent whose thermal expansion coefficient after hardening is not smaller than the thermal expansion coefficient of the rotating body.
According to this optical deflection apparatus, even when the thermal expansion coefficient of the adhesive agent is maximum, and the gap is generated between the magnet and rotating body at the time of high temperature, it can be filled up by the expansion of the adhesive agent. Therefore, the joint strength of the adhesive agent at the time of the temperature variation and specifically at the time of high temperature, can be prevented from being lowered.
In this case, when the Young""s modulus after the hardening of the adhesive agent is not more than 100 N/mm2, as described above, even when the temperature variation occurs, the strain due to the differential thermal expansion between the magnet and the rotating body with the polygon mirror is absorbed by the deformation of the adhesive agent, therefore, the flatness of the mirror of the polygon mirror can be improved, and further, the change of the balance characteristic is small. Further, the strength of the joint portion of the adhesive agent can be prevented from being lowered due to the temperature variation.
Further, yet another optical deflection apparatus of the present invention is characterized in that: it has a base member, a coil fixed to the base member, and a rotor unit which rotates to the base member, and the rotor unit has: a rotating body having the polygon mirror; a bearing provided on the rotating body; and a magnet fixed on the rotating body in opposite to the coil, wherein the bearing and the rotating body are jointed together by the adhesive agent whose Young"" modulus after hardening is not more than 100 N/mm2.
According to the optical deflection apparatus, as described above, even when the temperature variation occurs, because the strain due to the differential thermal expansion between the bearing and the rotating body with the polygon mirror is absorbed by the deformation of the adhesive agent, the flatness of the polygon mirror can be improved, and further, the change of the balance characteristic is small. Further, the strength of the joint portion of the adhesive agent can be prevented from being lowered due to the temperature variation.
Furthermore, further yet another optical deflection apparatus of the present invention is characterized in that: it has a base member, a coil fixed to the base member, and a rotor unit which rotates to the base member, and the rotor unit has: a rotating body having the polygon mirror; a bearing provided on the rotating body; and a magnet fixed on the rotating body in opposite to the coil, wherein the thermal expansion coefficient of the rotating body is not smaller than the thermal expansion coefficient of the bearing, and the bearing and the rotating body are jointed together by the adhesive agent whose thermal expansion coefficient after hardening is not smaller than the thermal expansion coefficient of the rotating body.
According to this optical deflection apparatus, even when the thermal expansion coefficient of the adhesive agent is the maximum, and the gap is generated at the time of high temperature between the bearing and the rotating body, the gap can be filled up by the expansion of the adhesive agent. Therefore, the joint strength of the adhesive agent at the time of the temperature variation, specifically at the time of high temperature, can be prevented from being lowered.
In this case, because the Young""s modulus of the adhesive agent after hardening is not more than 100 N/mm2, as described above, even when the temperature variation occurs, the strain due to the differential thermal expansion between the bearing and the rotating body with the polygon mirror is absorbed by the deformation of the adhesive agent, thereby, the flatness of the mirror of the polygon mirror can be improved, further, the change of the balance characteristic is small. Further, the strength of the joint portion of the adhesive agent can be prevented from being lowered due to the temperature variation.
Further, in addition to that the bearing and the rotating body are jointed together by the adhesive agent whose Young""s modulus after hardening is not more than 100 N/mm2, when the magnet and the rotating body are jointed together by the adhesive agent whose Young""s modulus after hardening is not more than 100 N/mm2, the flatness of the mirror of the polygon mirror is further improved, and further, the change of the balance characteristic is small. Further, the strength of the joint portion of the adhesive agent can be more prevented from being lowered due to the temperature variation.
Further, in addition to that the bearing and the rotating body are jointed together by the adhesive agent whose thermal expansion coefficient after hardening is not smaller than the thermal expansion coefficient of the rotating body, the magnet and the rotating body are jointed together by the adhesive agent whose thermal expansion coefficient after hardening is not smaller than the thermal expansion coefficient of the rotating body, thereby, the joint strength of the adhesive agent at the time of the temperature variation, specifically at the time of high temperature, can be more prevented from being lowered.
In this case, when the Young""s modulus after hardening of the adhesive agent to joint the bearing and the rotating body, and the magnet and the rotating body, is not more than 100 N/mm2 for both cases, the flatness of the mirror of the polygon mirror can be further improved, and further, the balance characteristic is not changed. Further, the strength of the joint portion of the adhesive agent can be more prevented from being lowered due to the temperature variation.
A production method of the optical deflection apparatus of the present invention which is a production method of the optical deflection apparatus having, a base member, a coil fixed to the base member, and a rotor unit which rotates to the base member, and the rotor unit has: a rotating body having the polygon mirror; a bearing provided on the rotating body; and a magnet adhered to the rotating body in opposite to the coil, and it is characterized in that: as the adhesive agent for the magnet, the anaerobic adhesive agent is used together with a hardening accelerator including amine organic compound, and when the surface on which the anaerobic adhesive agent is coated, and the surface on which the hardening accelerator is coated, are adhered together, the accumulated irradiation quantity of the light ray of the wavelength of not more than 400 nm on the surface on which the hardening accelerator is coated, is limited to not more than 1500 mJ/cm2, and preferably, to not more than 1000 mJ/cm2.
According to this production method, it can be effectively prevented that, when the ultraviolet ray (the light ray of the wavelength of not more than 400 nm) is irradiated on the coated surface of the hardening accelerator, the deterioration of the component of the hardening accelerator occurs and the adhesive agent is not hardened, and the magnet jointed by the adhesive agent is not easily peeled off, and the joint strength by the adhesive agent of the magnet of the optical deflection apparatus can be prevented from being lowered. Further, peeling off of the joint portion in the production or scattering of the not-hardened adhesive agent can be prevented, and the increase of the yield of the optical deflection apparatus and the quality, can be realized. Incidentally, the production method can be applied without specifically limiting the kind of the anaerobic adhesive agent, the Young""s modulus after hardening, and the thermal expansion coefficient.
Further, the adhering method of the present invention is an adhering method by which both surfaces are jointed together by using the anaerobic adhesive agent together with the hardening accelerator, which is characterized in that: when the surface on which the anaerobic adhesive agent is coated, and another surface on which the hardening accelerator is coated, are jointed together, the accumulated irradiation quantity of the light ray of the wavelength of not more than 400 nm on the coated surface of the hardening accelerator is limited to not more than 1500 mJ/cm2, preferably, to not more than 1000 mJ/cm2.
According to this adhering method, it can be effectively prevented that, when the ultraviolet ray (the light ray of the wavelength of not more than 400 nm) is irradiated on the coated surface of the hardening accelerator, the deterioration of the component of the hardening accelerator occurs and the adhesive agent is not hardened, and the jointed portion by the adhesive agent is. not easily peeled off, and the strength of the jointed portion by the adhesive agent can be prevented from being lowered. Further, peeling off of the joint portion by the adhesive agent or scattering of the not-hardened adhesive agent can be prevented, and the increase of the yield of the jointed portion in the production by the adhesive agent and the quality, can be realized.
Incidentally, in the present invention, the anaerobic adhesive agent is an adhesive agent in which, when it is in contact with the air, it is stable and does not react, and is not hardened, but, when the air is shut off, and it is in contact with the metal, it reacts and the hardening is started and advanced, and there is, for example, an acrylic anaerobic adhesive agent. Further, the hardening accelerator includes the metal, and thereby, the metal is made up for the start and advance of the hardening reaction.